{"72523":{"#nid":"72523","#data":{"type":"news","title":"Imaging Technique Shows Promise in Osteoarthritis","body":[{"value":"\u003Cp\u003EAn innovative combination of existing technologies shows promise for noninvasive, high-resolution imaging of cartilage in research on the progression and treatment of the common degenerative disease osteoarthritis.\n\u003C\/p\u003E\n\u003Cp\u003EMicrocomputed tomography (microCT) - which yields three-dimensional X-ray images with a resolution 100 times higher than clinical CT scans - is commonly used to image bone for osteoporosis research but has not been useful for imaging soft biological tissues such as cartilage. These tissues simply don\u0027t interfere with the microCT\u0027s X-rays as they pass through a sample, and therefore don\u0027t show up on scans.\n\u003C\/p\u003E\n\u003Cp\u003EBut by combining microCT with an X-ray-absorbing contrast agent that has a negative charge, researchers at the Georgia Institute of Technology were able to image the distribution of negatively charged molecules called proteoglycans (PGs). These molecules are critical to the proper functioning of cartilage.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022By detecting PG content and distribution, the technique reveals information about both the thickness and composition of the cartilage -- important factors for monitoring the progression and treatment of osteoarthritis,\u0022 said Associate Professor Marc Levenston in Georgia Tech\u0027s George W. Woodruff School of Mechanical Engineering.\n\u003C\/p\u003E\n\u003Cp\u003EHe and Associate Professor Robert Guldberg, also in the School of Mechanical Engineering, collaborated to establish and validate the principle of the technique, dubbed Equilibrium Partitioning of an Ionic Contrast agent-microCT, or EPIC-microCT. Then they applied the technique \u003Cem\u003Ein vitro \u003C\/em\u003Eto monitor the degradation of bovine cartilage cores and to visualize the thin layer of cartilage in an intact rabbit knee. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022This technique will allow pharmaceutical researchers to obtain more detailed information about the effects of new drugs and other treatment strategies for treating osteoarthritis,\u0022 Levenston said.\n\u003C\/p\u003E\n\u003Cp\u003EA report on the research will be published Dec. 19 in the journal \u003Cem\u003EProceedings of the National Academy of Sciences\u003C\/em\u003E and appeared in the online early edition on Dec. 4. The National Science Foundation, National Institute of Arthritis and Musculoskeletal and Skin Disorders, and the Arthritis Foundation funded the work.\n\u003C\/p\u003E\n\u003Cp\u003EExperiments conducted by Ph.D. student Ashley Palmer established the principles and protocol of EPIC-microCT. Researchers first immersed cartilage samples in the contrast agent solution and waited for the agent to diffuse into the tissue. Tissue with fewer negatively charged PGs absorbed more of the negatively charged contrast agent, and tissue with a higher PG concentration repelled it. \n\u003C\/p\u003E\n\u003Cp\u003EResearchers then used EPIC-microCT to detect the concentrations of the contrast agent, which allowed them to calculate the amount of PGs in different parts of the cartilage. Because degrading cartilage loses PGs over time, researchers could monitor the progression of tissue changes. In addition, differences in the X-ray signal of cartilage and bone allowed researchers to isolate the cartilage layer on a rabbit joint and determine its thickness, indicating that this technique also can be used to measure tissue thinning during disease progression. \n\u003C\/p\u003E\n\u003Cp\u003EIn follow-on research funded by a new, two-year grant from the National Institutes of Health, the researchers will gather additional quantitative data and use the technique to examine the very thin cartilage of rat knee joints. Researchers will nondestructively evaluate osteoarthritis progression and then attempt to use this approach to monitor cartilage changes over time \u003Cem\u003Ein vivo\u003C\/em\u003E, or inside the same live animals. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022Ultimately, if we can monitor cartilage changes with good resolution and do it with little or no invasion of the tissue in live animals, then we can track osteoarthritis progression and the effects of drug therapy or other treatments over time,\u0022 Guldberg said.\n\u003C\/p\u003E\n\u003Cp\u003EResearchers have already addressed a significant technical hurdle in making the imaging technique feasible. They researched several contrast agents and tried two others before choosing HexabrixTM, which is approved by the Food and Drug Administration for use as a contrast agent for various imaging procedures in humans. When diluted, it produced an X-ray signal that allowed distinction of bone from cartilage. \n\u003C\/p\u003E\n\u003Cp\u003E\u0022The ability to separate bone from cartilage in the microCT scan is a big deal,\u0022 Guldberg said. \u0022It suggests that this technique may work in vivo.\u0022 \n\u003C\/p\u003E\n\u003Cp\u003EBut dilution reduces the contrast agent\u0027s sensitivity and therefore the technique\u0027s PG-monitoring capability, the authors write in their paper. \u0022In this next phase of research, we hope to find a one-shot concentration of the contrast agent that works for analyzing both cartilage thickness and composition,\u0022 said Levenston, the senior author on the paper. \n\u003C\/p\u003E\n\u003Cp\u003EIn addition, the researchers must address technical issues involving the \u003Cem\u003Ein vivo \u003C\/em\u003Edelivery and retention of a sufficient volume and concentration of the contrast agent, they note in the paper.\n\u003C\/p\u003E\n\u003Cp\u003E\u0022But even if the technique only works for in vitro studies, it still provides useful quantitative, high-resolution, 3D images that researchers can use to nondestructively monitor cartilage degeneration and even regeneration in small animal models,\u0022 Guldberg said. \n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\nGeorgia Institute of Technology\u003Cbr \/\u003E\n75 Fifth Street, N.W., Suite 100\u003Cbr \/\u003E\nAtlanta, Georgia  30308  USA\u003C\/strong\u003E\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contact\u003C\/strong\u003E: John Toon (404-894-6986); E-mail: (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E).\n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003ETechnical Contacts\u003C\/strong\u003E: Robert Guldberg (404-894-6589); E-mail:  (\u003Ca href=\u0022mailto:robert.guldberg@me.gatech.edu\u0022\u003Erobert.guldberg@me.gatech.edu\u003C\/a\u003E); Ashley Palmer (404-385-6779); E-mail: (\u003Ca href=\u0022mailto:ashley.palmer@gatech.edu\u0022\u003Eashley.palmer@gatech.edu\u003C\/a\u003E). \n\u003C\/p\u003E\n\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E:  Jane M. Sanders\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"High-resolution imaging with contrast agent aids disease research"}],"field_summary":[{"value":"An innovative combination of existing technologies shows promise for noninvasive, high-resolution imaging of cartilage in research on the progression and treatment of the common degenerative disease osteoarthritis.","format":"limited_html"}],"field_summary_sentence":[{"value":"New imaging technique aids osteoarthritis research"}],"uid":"27303","created_gmt":"2006-12-05 01:00:00","changed_gmt":"2016-10-08 03:03:29","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2006-12-05T00:00:00-05:00","iso_date":"2006-12-05T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"72524":{"id":"72524","type":"image","title":"Ashley Palmer","body":null,"created":"1449177934","gmt_created":"2015-12-03 21:25:34","changed":"1475894658","gmt_changed":"2016-10-08 02:44:18"},"72525":{"id":"72525","type":"image","title":"Images from new technique","body":null,"created":"1449177934","gmt_created":"2015-12-03 21:25:34","changed":"1475894658","gmt_changed":"2016-10-08 02:44:18"}},"media_ids":["72524","72525"],"related_links":[{"url":"http:\/\/www.me.gatech.edu\/","title":"George W. Woodruff School of Mechanical Engineering"},{"url":"http:\/\/www.me.gatech.edu\/fac_staff\/ac_fac\/academic.faculty\/Levenston_Marc.html","title":"Marc Levenston"},{"url":"http:\/\/www.me.gatech.edu\/fac_staff\/ac_fac\/academic.faculty\/Guldberg_Robert.html","title":"Robert Guldberg"}],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"146","name":"Life Sciences and Biology"},{"id":"135","name":"Research"}],"keywords":[{"id":"569","name":"bioengineering"},{"id":"7594","name":"cartilage"},{"id":"5302","name":"Disease"},{"id":"987","name":"imaging"},{"id":"7593","name":"Osteoarthrisis"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cstrong\u003EJohn Toon\u003C\/strong\u003E\u003Cbr \/\u003EResearch News \u0026amp; Publications Office\u003Cbr \/\u003E\u003Ca href=\u0022http:\/\/www.gatech.edu\/contact\/index.html?id=jt7\u0022\u003EContact John Toon\u003C\/a\u003E\u003Cbr \/\u003E\u003Cstrong\u003E404-894-6986\u003C\/strong\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}